I agree with AK, and also have been on the Vision.
For excursions, we usually do the glass bottom boat ride to Los Arcos in Cabo ($12 at the pier). In Mazatlan, we normally take the excursions out of the city (our least favorite port). The colonial town tour is very nice. We also did a city tour last time ($13 at the pier through Marlin Tours). Puerto Vallarta is a great walk-around town. Check out the Rio Cuale and then lunch on the Malecon. Van to town is $4 for 2 and cab ride back is about $5.
Hope that helps.